#include<stdio.h>
#include<string.h>
int main()
{
    char a[101],b[101];
    int top,next,len,i,mid;

    gets(a);
    len=strlen(a);
    mid=len/2-1;

        top=0;
    for(i=0;i<=mid;i++)
        b[++top]=a[i];

    if(len%2==0)
        next=mid+1;
    else
        next=mid+2;

    for(i=next;i<=len-1;i++)
    {
            if(a[i]!=b[top])
            break;
        top--;
    }

    if(top==0)
        printf("YES");
    else
        printf("NO");

    getchar();getchar();
    return 0;
}
